وَيْلٌۭ لِّلْمُطَفِّفِينَ ﴿١﴾
Woe to those who give less [than due],
Haram Money & business
Is cheating in business haram?
Short answer
Yes. The Quran warns: woe to those who give less than is due, and commands full measure and weight (83:1-3, 11:85). The Prophet ﷺ said: he who deceives is not of me.
Evidence
Quran
ٱلَّذِينَ إِذَا ٱكْتَالُوا۟ عَلَى ٱلنَّاسِ يَسْتَوْفُونَ ﴿٢﴾
Who, when they take a measure from people, take in full.
وَإِذَا كَالُوهُمْ أَو وَّزَنُوهُمْ يُخْسِرُونَ ﴿٣﴾
But if they give by measure or by weight to them, they cause loss.
وَيَٰقَوْمِ أَوْفُوا۟ ٱلْمِكْيَالَ وَٱلْمِيزَانَ بِٱلْقِسْطِ ۖ وَلَا تَبْخَسُوا۟ ٱلنَّاسَ أَشْيَآءَهُمْ وَلَا تَعْثَوْا۟ فِى ٱلْأَرْضِ مُفْسِدِينَ ﴿٨٥﴾
And O my people, give full measure and weight in justice and do not deprive the people of their due and do not commit abuse on the earth, spreading corruption.
Hadith
Sahih Muslim 102
It is narrated on the authority of Abu Huraira that the Messenger of Allah (ﷺ) happened to pass by a heap of eatables (corn). He thrust his hand in that (heap) and his fingers were moistened. He said to the owner of that heap of eatables (corn):What is this? He replied: Messenger of Allah, these have been drenched by rainfall. He (the Holy Prophet) remarked: Why did you not place this (the drenched part of the heap) over other eatables so that the people could see it? He who deceives is not of me (is not my follower)
Arabic text (with chain of narrators)
وَحَدَّثَنِي يَحْيَى بْنُ أَيُّوبَ، وَقُتَيْبَةُ، وَابْنُ، حُجْرٍ جَمِيعًا عَنْ إِسْمَاعِيلَ بْنِ جَعْفَرٍ، - قَالَ ابْنُ أَيُّوبَ حَدَّثَنَا إِسْمَاعِيلُ، - قَالَ أَخْبَرَنِي الْعَلاَءُ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، . أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم مَرَّ عَلَى صُبْرَةِ طَعَامٍ فَأَدْخَلَ يَدَهُ فِيهَا فَنَالَتْ أَصَابِعُهُ بَلَلاً فَقَالَ " مَا هَذَا يَا صَاحِبَ الطَّعَامِ " . قَالَ أَصَابَتْهُ السَّمَاءُ يَا رَسُولَ اللَّهِ . قَالَ " أَفَلاَ جَعَلْتَهُ فَوْقَ الطَّعَامِ كَىْ يَرَاهُ النَّاسُ مَنْ غَشَّ فَلَيْسَ مِنِّي " .
This is general information, not a fatwa. For your own situation, ask a qualified scholar.
Questions about halal and haram
Is cheating in business haram?
Yes. The Quran warns: woe to those who give less than is due, and commands full measure and weight (83:1-3, 11:85). The Prophet ﷺ said: he who deceives is not of me.